1. Field of the Invention
The present invention relates to a key switch assembly for a computer keyboard, more particularly to a key switch assembly which includes a key cap support with an enhanced strength and which can be easily assembled.
2. Description of the Related Art
U.S. Pat. No. 5,457,297 discloses a conventional key switch assembly which includes a key cap, a bridging device, a bridging device supporting board, a key base, a membrane circuit and a bottom support board. The bridging device includes first and second rectangular frames pivotally connected together into a crossed form. Each of the first and second rectangular frames comprises two parallel rods and two transverse rods connected between the two parallel rods. The parallel rods of the first rectangular frame have intermediate portions formed with pin holes. The parallel rods of the second rectangular frame have two inward pins inserted respectively and inwardly into the pin holes of the first rectangular frame for coupling pivotally the first and second rectangular frames.
When the key switch assembly is used in a notebook computer, the intermediate portions of the first and second rectangular frames are typically made to have a width of about 1.6 millimeters, while the pin holes and the inward pins have diameters of only about 1 millimeter in order to minimize the height of the key switch assembly. As such, the pins might break or the pin holes might be damaged when a relatively large force is applied on the key cap. Therefore, the strength of the coupling between the first and second rectangular frames is not satisfactory. In addition, during assembly, the parallel rods of the second rectangular frame must be bent away from each other so that the inward pins can be registered with the relatively small pin holes for insertion into the pin holes. Assembly of the bridging device is thus difficult to conduct.
In co-pending U.S. patent application Ser. No. 08/918,048, the Applicant disclosed a key switch assembly with a key cap support which includes first and second support levers coupled rotatably about a pivot axis such that the key switch assembly has an increased coupling strength and which can be easily assembled.